Thanks, rockzmom. It does help. Actually I was struggling with "Acutes" and came to the conclusion that they are just opposite in some way to "Chronics". On the other hand for a non native much more difficult are the words which are simple every day words for an American but used in some specific way which is not obvious for a non native. For an example it took me quite a long time to get that the "Greens" is a sort of patient's clothes.